1. Field of the Invention
The present invention relates to a terminal block structure unlikely to loosen and easy to assemble.
2. Description of the Prior Art
Terminal blocks are widely used in implementation of electrical signal transmission and electrical connection. FIG. 7 shows a conventional terminal block structure which includes a base 80. The base 80 is provided with one or more terminal recesses 81 thereabove. A retaining socket 82 is provided at the middle of the terminal recess 81. The retaining socket 82 is substantially hexagonal in shape and is configured to receive a nut 70 therein (seeing FIG. 8). Referring to FIG. 7, a holder 60 is disposed inside the terminal recess 81. A platform 61 is formed on the top surface of the holder 60, and is centrally formed with a through hole 62. The holder 60 is flanked by two inserts 63 provided with a barb each. The holder 60 is inserted into the terminal recess 81 by a force and is stopped when the inserts 63 abut against the inner wall of the terminal recess 81, and in consequence the holder 60 is fixed in position and cannot be released from the terminal recess 81. A terminal pin 64 configured to facilitate electrical signal transmission is provided at the end of one of the inserts 63 of the holder 60.
A fastener 50, which may be a screw or a bolt, has a stud provided with a pad 51 thereabove. A clamping surface against which a terminal head (not shown) abuts is defined between the pad 51 and the platform 61 of the holder 60. The fastener 50 penetrates the through hole 62 of the holder 60, and is screwed to the nut 70. In so doing, a terminal block structure is finalized.
However, in practice, the fastener 50 tends to rotate and loosen and thereby allows the nut 70 to be released from the retaining socket 82; as a result, loosening of the fastener 50 often follows second screwing. The defect renders an assembly process difficult, and is a major drawback of the prior art.
Also, the retaining socket 82 is fabricated by trenching in another recess, and thus the fabrication process of the retaining socket 82 is time-consuming and laborious. Furthermore, the retaining socket 82 is too shallow to hold the nut 70 firmly, and in consequence the nut 70 tends to loosen. The above-mentioned fact represents another drawback of the prior art.
Referring to FIG. 9, in addition to the base 80 shown in FIG. 7, another conventional terminal block structure comprises a holder 90 centrally formed with a screw hole 91 configured to replace known said base 80 shown in FIG. 7. The design is seemingly good in that it dispenses with a component required for the prior art, but in practice the design has a flaw. That is, to form the screw hole 91 in the holder 90, the holder 90 must be made from brass (alloy of copper and zinc). From the perspective of material science, brass has its own drawbacks. Pure copper cannot be tapped to form the screw hole 91 with expected efficacy. The above-mentioned fact represents a further drawback of the prior art.
Yet a further drawback of the prior art is described below. Where the holder 90 has an additional purpose, namely, serving as a nut, the holder 90 has to bear a screwing force. The resultant problem is that, a terminal pin which is indispensable to the holder 90 bears the screwing force directly and therefore is likely to bend or crack, and in consequence contacts between the terminal pin and solder are vulnerable.